First a soldier guarding a hallowed war memorial was gunned down in Canada's capital. Then shots erupted in the halls of the country's Parliament minutes later.
The two shootings in Ottawa Wednesday left lawmakers barricaded inside offices and parts of the city on lockdown for hours as police searched for suspects.
Ottawa Police lifted the lockdown Wednesday night and said there was no longer a danger to the public.
But many questions remain about the shootings: Who was the gunman? Why did he open fire? And was he acting alone?
"It appears there was just one shooter, and that shooter is dead," Ottawa Mayor Jim Watson told CNN's Anderson Cooper. "But it has been a traumatic experience, obviously, for not only our city but the country."
Investigators haven't provided any possible motives for the shooting. Canadian Prime Minister Stephen Harper didn't provide details about the investigation in a televised address to the nation Wednesday night.
"In the days to come, we will learn more about the terrorist and any accomplices he may have had, but this week's events are a grim reminder that Canada is not immune to the types of terrorist attacks we have seen elsewhere in the world," Harper said. "Let there be no misunderstanding: We will not be intimidated. Canada will never be intimidated."
It is unclear whether additional suspects were tied to the shootings or whether additional arrests have been made. The Royal Canadian Mounted Police said more information would be provided in a press conference Thursday.
As authorities continued to investigate, details began to emerge about the man they suspect was behind the shooting.
Michael Zehaf-Bibeau was identified by Canadian officials to their American counterparts as the suspected gunman, multiple U.S. officials told CNN.
Bibeau, who was born in 1982, was a convert to Islam and had a history of drug use before he converted, two sources said.
His passport had been confiscated by Canadian authorities when they learned he planned to go fight overseas, a U.S. law enforcement official told CNN's Susan Candiotti. The official said it was not clear when that happened.
Canadian broadcaster CBC reported that Bibeau had a record of drug arrests going back 10 years.
See more on this developing story on CNN.com
The heart of a small town in Quebec is now a scorched disaster zone after a runaway freight train carrying 73 cars of crude oil derailed and exploded there, bursting into flames.
Twenty people are confirmed dead, with 30 still missing and presumed killed in the inferno.
The death toll continues to rise in the aftermath of that deadly train explosion in Lac Megantic, where angry residents are demanding answers.
CNN’s Anna Coren has their story.
“Police say they've found evidence of tampering on the locomotive and have launched a criminal investigation,” Coren reports.
“Separately, the engineer has been suspended without pay over whether or not enough brakes were engaged on the train. But that didn't stop local residents from directing their anger at the train company as this mourning township demands answers.”
“It's a bomb that is on the railroad," local resident Patrice Laframbuise says. “Why is it normal that this is acceptable?”
New details about the deadly train crash and explosion in Lac-Megantic, Quebec is raising new questions this morning.
At least 15 people are now confirmed dead and 35 remain missing after the runaway train loaded with 72 tankers of crude oil derailed and exploded, obliterating the center of the town.
Initially reported as an accident, the crash is now being investigated as a possible criminal act.
CNN’s Paula Newton has details.
“It's clear police want to preserve the heart of what is now a crime scene,” Newton reports. “They've asked firefighters to stop dousing it with water. They have dozens of investigators combing through what little is left.”
Police are revealing little about what evidence they’ve uncovered from the catastrophe, but they are not convinced it was purely an accident.
"Namely there are pieces that lead us to believe that there are certain facts that might lead to criminal acts,” says Captain Michel Forget of the Quebec Provincial Police.
CNN is reporting a horrific runaway train disaster in Canada this morning.
A train loaded with crude oil derailed, crashed and exploded into flames in Lac-Megantic, Quebec.
At least five people are dead and another 40 still unaccounted for after the disaster. Authorities expect the death toll to climb.
Canadian Prime Minister Stephen Harper says the small Canadian town now looks like a "war zone".
CNN’s Paula Newton is live in Lac-Megantic with details.